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The director of intelligence at U.S. Cyber Command said the command has the capacity to significantly damage a country's infrastructure if necessary.

Rear Adm. Samuel Cox said such an attack would only come after officials at the highest levels of government approved the operation because there would be a risk of collateral damage, the Associated Press reported.

Cox also said the "resiliency and redundancy" built into the a nation's power grid and internet infrastructure would make it difficult to knock them completely offline.